Dosing Considerations Heparin Sodium in 5% Dextrose Injection is indicated as a continuous intravenous infusion following an initial intravenous therapeutic dose of heparin sodium. The product should be administered under the supervision of a qualified health professional who is experienced in the use of anticoagulant agents and in the management of patients with venous thrombosis, pulmonary embolism, acute and chronic consumptive coagulopathies and peripheral arterial embolism.
Appropriate management of therapy and complications is only possible when adequate diagnostic and treatment facilities are readily available. The dosage of heparin sodium should be adjusted according to the patient’s coagulation test results.
When heparin sodium is administered by continuous intravenous infusion, coagulation tests should be performed approximately every 4 hours during the early stages of therapy. 5 to 3 times the control value. Periodic platelet counts, hematocrits, and tests for occult blood in stool are recommended during the entire course of heparin therapy, regardless of the route of administration.
When an oral anticoagulant of the coumarin or similar type is to be begun in patients already receiving heparin sodium, baseline and subsequent tests of prothrombin activity must be determined at a time when heparin activity is too low to affect the prothrombin time.
This is about 5 hours after the last IV bolus and 24 hours after the last subcutaneous dose. If continuous IV heparin infusion is used, prothrombin time can usually be measured at any time. In converting from heparin to an oral anticoagulant, the dose of the oral anticoagulant should be the usual initial amount and thereafter prothrombin time should be determined at the usual intervals.
To ensure continuous anticoagulation, it is advisable to continue full heparin therapy for several days after the prothrombin time has reached the therapeutic range. Heparin therapy may then be discontinued without tapering. Recommended Dose and Dosage Adjustment Although dosage must be adjusted for the individual patient according to the results of suitable laboratory tests, the following dosage schedules may be used as guidelines: Method of Administration Frequency Recommended dose1 Initial dose 5,000 units by IV injection.
Continuous intravenous Continuous 20,000 - 40,000 units/24 hours. infusion 1Based on 150-lb. (68-kg) patient. 12 12 Pediatric Use Follow recommendations of appropriate pediatric reference texts.
In general, the following dosage schedule may be used as a guideline:
Initial Dose: 50 units/kg (IV, drip). Maintenance Dose: 20,000 units/m2/24 hours continuously. Geriatric Use Patients over 60 years of age may require lower doses of heparin. ) Missed Dose The product should only be administered under the supervision of a qualified health professional who is experienced in the use of anticoagulant agents, and missed doses are not to be expected.
Administration Heparin Sodium in 5% Dextrose Injection is for continuous intravenous use only. Do not use Heparin Sodium in 5% Dextrose Injection as a “catheter lock flush” product. Confirm the choice of the correct heparin drug product and strength prior to administration of the drug to the patient (see Warnings and Precautions box).
Heparin sodium injection products must not be confused with “catheter lock flush” products. Heparin Sodium is not effective by oral administration and Heparin Sodium in 5% Dextrose Injection should not be given orally. This product should not be infused under pressure.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Drug Compatibility Because dosages of this drug are titrated to response no additives should be made to Heparin Sodium in 5% Dextrose Injection.
OVERDOSAGE For management of a suspected drug overdosage, contact your regional Poison Control Centre.
Symptoms:
Bleeding is the chief sign of heparin overdosage. Nosebleeds, blood in urine or tarry stools may be noted as the first sign of bleeding. Easy bruising or petechial formations may precede frank bleeding.
Treatment:
Neutralization of heparin effect. When clinical circumstances (bleeding) require reversal of heparinization, protamine sulfate (1% solution) by slow infusion will neutralize heparin sodium. No more than 50 mg should be administered, very slowly, in any 10 minute period.
Each mg of protamine sulfate neutralizes approximately 100 USP Heparin Units. The amount of protamine required decreases over time as heparin is metabolized. Although the metabolism of heparin is complex, it may, for the purpose of choosing a protamine dose, be assumed to have a half-life of about 1/2 hour after intravenous injection.
13 13 Administration of protamine sulfate can cause severe hypotensive and anaphylactoid reactions. Because fatal reactions often resembling anaphylaxis have been reported, the drug should be given only when resuscitation techniques and treatment of anaphylactoid shock are readily available.
For additional information the labeling of Protamine Sulfate Injection, USP products should be consulted. ACTION AND CLINICAL PHARMACOLOGY Mechanism of Action Heparin inhibits reactions that lead to the clotting of blood and the formation of fibrin clots both in vitro and in vivo.
Heparin acts at multiple sites in the normal coagulation system. Small amounts of heparin in combination with antithrombin III (heparin cofactor) can inhibit thrombosis by inactivating activated Factor X and inhibiting the conversion of prothrombin to thrombin.
Once active thrombosis has developed, larger amounts of heparin can inhibit further coagulation by inactivating thrombin and preventing the conversion of […]